Which of these is the better intake port?

[Anders]

I'm evaluating two Mopar small block heads which have nearly equivalent intake runner cross sectional area and port volume, but they differ in a few key areas. After flowing them both, I'm not sure which would make more power. Hoping to get some opinions.

The first head has a 2.200 intake valve with a 45 degree valve seat. The flow numbers are as follows:

.300 - 234 cfm
.400 - 299
.500 - 347
.600 - 383
.700 - 392
.800 - 400
.900 - 405

The second head has a 2.220 intake valve with a 52 degree valve seat. The flow numbers are as follows:

.300 - 231 cfm
.400 - 295
.500 - 360
.600 - 398
.700 - 420
.800 - 403
unfortunately I have no .900 numbers on this head

The second head seems a bit better, but I'm concerned by how it backs up above .700 especially considering the valve lift will likely be greater than .800. Which head do you all think will make better power? The application is a 430" drag race engine which will be run to about 8500.

[headman]

Flow numbers are only part of the picture, but the first head may actually be the better head.
The way the lower lift numbers are down on the second head really looks like a bowl area that is over size.

there must be turbulence in the second head for it to drop back at high lift.

[bill jones]

-you guys that are experiencing the reversal in high lift flow might be chasing your tail if you haven't investigated the possibility of your radius inlet doing tricks to you.
-If you can move your hand around or about the entrance of the radius, do ANYTHING that makes the manometers talk to you either good or bad, then you need to work on getting the radius's built right so that they don't cause the turbulence.
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-One other thing might be the variation in the height of the exhaust valve being too high or too thick a margin in relation to the intake so the exhaust valve is upsetting the intake flow.

[Anders]

I flowed the head on a 4.155 bore although it will be run on a 4.185 bore. I didn't have a bigger adapter to use on the flow bench. I wonder if the bigger bore might help the problem. I would really like to get this problem figured out because the .700 figure on the second head is awsome. If I could figure out how to get it to carry that figure to .900, I think I'd really have something.

I also need to try flowing it with the intake on it. The manifold runner is 5" long and has a round 2.5" opening. Maybe the manifold will have an effect on the high lift numbers, but I doubt it.

[bill jones]

-I can guarantee you that if you have only flowed one port up until now, you need to be flowing every port when you are searching for answers to this condition.
-You'll almost invaribly find a variation among the ports, especially if they are hand ported, and you might get lucky and find one port that does something extra special good that you can look at real close and make templates of it to check against the poor flowing ports.
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-If you can't flowtest a set of ports to .900" lift in about 40 to 50 minutes then you need to get the tooling up to speed on the flowbench, get your exact flowtesting procedure down so you can do it really quick.
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-I would also be bolting the head onto an empty block and look up in the bore to see exactly how the heads fits the bore, and then making sure the flowbench head perch is exactly the same or at the least pretty darn close.

[RyanJ]

These must be P7 heads? Or else bench is high for Wedge W7/8/9/9RP stuff.

Alot of factors.

What intake is going on this thing, Cast or Sheet Metal? If Cast, is it a restrictor plate intake or non plate. (they are vastly different as I'm sure you know)

What back cuts on the valves of each head? Specifically the 52* seat version.

What bench were these on (what test pressure) Can you put more airspeed through the 52* seat head than whatever you tested it at before? Any velocity #'s on these two heads?

[Anders]

They are W9RP wedge heads and the flowbench is a SF-600 at 28 in of water. The backcut is 30 degrees on the 45 degree head and 35 degrees on the 52 degree head. Both heads were cnc ported, but they have both been worked a bit by hand as well.

Unfortunately, I don't have any velocity numbers to share.

I suspect the problem is in the seat area. What do you think about the back cuts on the valves? I'd like to try a couple more degrees on the 52 degree valves, but I'd hate to ruin a brand new titanium valve if I'm wrong.

[w5dart66]

Well If you can today do a 52*W/a 37* BC I think you will see a big gain.Ryan should post to this he did 52* W/like 3~4 different BCs and the 37* killed all the other ones.let us know if you try it.

[cboggs]

I might be able to shed some light on this one.

The W9 rp's can flow a ton, so the 420 - 430 numbers don't surprise me.

I think the head with the 52º seat will be a better head when the
high lift problem is solved. Have a look at the numbers, you're
giving up a few cfm at lower lifts for a BIG gain at mid & high lifts.
At the ramp speed of current roller cams, .. the second head will be
better once the high lift turbulence is fixed. The 52º seat will wet flow better.

.300 - 234- 231-3
.400 - 299-295-4
.500 - 347-360+13
.600 - 383-398+15
.700 - 392-420+18
.800 - 400-??
.900 - 405-??

The head that's backing up, .. I assume it starts making noise on the
flow bench when it backs up? You can hear the air separate?

The key is around the valve job of course, .. but the 52º seat might
want a different short turn profile. I'd do a very detailed velocity map
of the port, .. short turn, .. and flip the head over on the bench and
map the velocity coming out around the valve. Do this at a lift where it
doesn't separate, and at a lift where it does.

All of this should identify the area where the separation happens
and what it will want.

I'd probe the port with some string or "flow balls" to make sure
I find the "spot" as well.

I'd bet the short turn is the spot, ..

Once you've done this you can e-mail / call me if needed.
(shop - 703-541-0565 )

I would agree with the 37º back cut, .. it's 15º from the seat angle
just like your 45º seat back angle of 30º.
I'd get a few stainless valves of the same profile of the titanium to
test with if the budget doesn't allow sacrificing a few titanium valves.

What do you have for a top angle on the 52º seat??
Actually, .. what are all the angles on the seat, above & below?

I assume these are CnC ported by Chapman and hand worked.
So is there any difference in cross section between the head with the
2.200" valve and the one with the 2.220" valve??

I'd do some tests above 28" h2o also, .. flow at 36" or so to make sure
the port is whisper smooth.

I'm building a very similar set up. 412" with W9 rp's, sheet metal intake, etc.

Curtis

[maxracesoftware]

-you guys that are experiencing the reversal in high lift flow might be chasing your tail if you haven't investigated the possibility of your radius inlet doing tricks to you.
-If you can move your hand around or about the entrance of the radius, do ANYTHING that makes the manometers talk to you either good or bad, then you need to work on getting the radius's built right so that they don't cause the turbulence. --Bill Jones

Bill, glad to see someonelse has come across this before.
sometimes you have to tryout a Radius Entry thats 1.000"+ thick
some Cyl Heads that have too much a difference between the Roof -vs- Floor Lengths can also cause this.

-I can guarantee you that if you have only flowed one port up until now, you need to be flowing every port when you are searching for answers to this condition.
-You'll almost invaribly find a variation among the ports, especially if they are hand ported, and you might get lucky and find one port that does something extra special good that you can look at real close and make templates of it to check against the poor flowing ports.

again Bill...great advice...i do the same thing when i'm having a problem with 1 particular port -vs- the others.


when i Shape the Short Turn area..i try very hard to create a Shape that will eliminate or greatly reduce the "Short Turn Sensitivity"
the Short Turn should be Shaped to work great with either No-BackCut or with a BackCut Angle.....it shouldn't rely solely on the BackCut angle to Flow well....because you are dry Flow testing...when heavier Fuel mixture
trying to make that Short Turn, if its too sensitive it can cause separation in a Live Engine .

[Anders]

Thank you all for your helpful suggestions. I have ordered an extra stainless valve for experimenting with different back cuts.

When the port backs up, you can indeed hear the turbulence. It's not terribly loud, but the sound of the port does change over .700. In fact, at .750 the flow is down to 405.

I'm trying to remember some of your questions here. The intake is sheet metal and the round 2.5" port openings in the plenum taper down to the port over their 5" length.

There is very little cross sectional difference between the two. One major difference is that the 52 degree head has had the valve centerlines moved around slightly. The exhaust valve is tighter. against the cylinder wall and the intake is moved over slightly toward the center of the cylinder. The 52 degree head also has a more prominant vane surrounding the guide boss.

The short turn is to my eyes identical on both heads. Would the optimal short turn radius be different based solely on the different seat angle?

[cboggs]

There is very little cross sectional difference between the two. One major difference is that the 52 degree head has had the valve centerlines moved around slightly. The exhaust valve is tighter. against the cylinder wall and the intake is moved over slightly toward the center of the cylinder. The 52 degree head also has a more prominant vane surrounding the guide boss.

The short turn is to my eyes identical on both heads. Would the optimal short turn radius be different based solely on the different seat angle?

Anders,

I still think this is a short turn problem, .. the 52º seat will want a
little different short turn. BUT as larry said, .. it shouldn't be THAT sensitive.
Some times the bottom angle will play hell with it too, ... what angles
are under the seat angle, are they left sharp or blended.

Here's the big one, .. it's a CnC head, .. did it do this BEFORE the hand
work?? If not, . . what got hand worked?

Another thing to look at is the top seat angles and the transition
into the chamber, .. but for it to sepperate like that i'd have
to be fairly messed up. But that's why I said to map the
port to make sure where the problem is.

Have you tried flow balls in the port to see if you can smooth
out the flow?

Take a little metal ball, 1/8" or smaller, .. weld to the end of a
welding rod. Use that to probe in the port and see if flow goes
up or the sound smooths out. This will tell you what's going on.
If you put the flow ball on the floor an inch or two before the
short turn and flow goes up and the sound smooths out, ..
the short turn needs work and this indicates the apex is too sharp.

Curtis

[RyanJ]

I'd like to know what all the seat angles are as well.

On the stuff I have played with I have a 52* Sunnen VSC seat cutter, 45* top cut, 65* bottom. and hand blend to the 45 and 65. I have used that cutter on W7's, W8's and W9's. With varying success. Most of them CNC out of one shop or another. Chapman, Coleman, Arrington etc. With those seat angles on a hand ported W7 with a concave chamber I tetsed a bunch of different back cuts on same Ferrea Part # valves. I tried, 37, 35, 33, 40, 45 and 31. Everything helped a little (1-2).... but the 37 was head and shoulders above the rest. I think it was worth about 8 cfm @ .500" and was definitely the best "sounding" of the group. Every head is different but was just funny to see 15 off the seat work like that.

Curtis I need to see those W9 RP's when you get them done. I'd love to see if they can put up anywhere near 360 @ .500" on Rider Racings SF600. If they do, I will have to buy another set and convince you to let me use your CNC program on mine LOL. I know Brett has now had 3 sets of 50* seat Arrington 8's on it and none over 301 @ .500.. 45* seat Chapman W7 was 315ish?

Oh and Anders have you flowed the head with no intake valve?

[Anders]

The valve job is similar to yours Ryan, but there is an additional bottom cut below the 65. The botom cut looks to be less than 90, but I'm not exactly sure what it is. All the angles are sharp and there is no blending the bottom cut into the runner. The top cut is blended to the chamber.

The port did exactly the same thing before the hand work which consisted mostly of streamlining the guide boss and the exposed end of the valve guide. Following this work, the port picked up 9 cfm average, but still backed up at high lift.

I have not flowed the port without the valve, but that would be very interesting.

[cboggs]

Anders,

My guess would be the second bottom angle is something like an 82º
I'd leave them sharp and not blend the bottom angles, .. don't let
the flow bench lie to you about that.

Who did the CnC work? If I knew that, there's a chance I might
know the port.

Did you try the flow ball test along the floor of the port?
The W9rp has a very tall and long short turn but can be tricky.

Perhaps you should make a port mold, .. then measure the csa's.
Also Ryan's point of flowing the head without the valve is good, ..

If you want, get the thing on the bench, .. ready to flow then call me
and we can work through some things over the phone.

Ryan, .. if you want to use my CnC program for the W9rp's it'll cost ya, .
maybe a pizza & Coke, .. ..

Curtis